Medical shaft-type instruments are already known from prior art, such as from EP 0 697 198 A1. This document discloses a surgical application device for clips. In order to allow a reuse of the essential parts of the application device in a surgical application device provided for U-shaped clips and comprising a handle, a tube shaft connecting thereto, a pincer-shaped contact tool on the free end of the tube shaft and a clip magazine in the tube shaft, comprising a closure mechanism for the contact tool which can be actuated from the handle and is arranged in the tube shaft, and comprising a feed motion mechanism for the clips which can also be actuated from the handle and is arranged in the tube shaft, said document suggests to provide the tube shaft with a lateral opening in which the clip magazine can be detachably inserted from outside in such a manner that it becomes operatively connected with the feed motion mechanism and that the outlet of the clip magazine is aligned with a feed motion path guiding the clips into the contact tool.
Such a clip magazine is also known from DE 10 2009 018 820 A1. In order to the simplify the construction of the magazine and to reduce the size with a magazine comprising a plurality of C-shaped ligature clamps, a housing receiving the ligature clamps which are arranged serially in a row and parallel to one another, a transport element which is able to reciprocate relative to the housing in the direction of the row and causes at least one a ligature clamp to advance toward the outlet end of the magazine upon the forward and backward motion relative to the housing, this document suggests that the ligature clamps each comprise two legs connected via a bridge portion and are subdivided by a longitudinal slit in two portions adjoining each other and connected to each other in the area of the free ends of the leg, and that the transport element penetrates the ligature clamps arranged in a row in the intermediate space between the two adjoining portions of the ligature clamp.
Thus, these existing devices use surgical clamps or clips which are also already known in principle.
By way of example, the company Applied Medical sells a surgical clip named EPIX Universal CA500, in which the two essentially straight clamp webs/legs/clip arms are connected to each other by a substantially V-shaped portion. The two straight clip arms extend substantially parallel to the longitudinal axis of the surgical clip and in the transition zones between the clip arms and the connecting portion, and relative small bending radii are provided in the area of the fillet of the connecting portion. This means that the transition zones are formed by kinks. Comparable surgical clips having a comparable geometry are also marketed by United States Surgical under the name Endo Clip Autosuture 5 mm and by Ethicon under the name Ligamax 5. The Endo Clip Autosuture III 5 mm likewise sold by United States Surgical has a somewhat different geometry. This clip also comprises two substantially straight, parallel clip arms as well as a connecting portion for the two straight clip arms, which is formed with a fillet having a quite small radius of curvature. Other than the surgical clips described above, the transition zones between the clip arms and the connecting portion are formed so as to have a considerably larger radius of curvature, so to speak rather as bent portions than as kinked portions. The Patent application US 2011/0224701 A1 discloses a surgical clip comprising a semicircular outer surface and a profiled inner surface. The semicircular outer surface serves to prevent the clip from getting wedged in the jaw part of a clip applicator and the profiled inner surface serves to improve the adherence on the clamped tissue. As seen in a side view, the clip arms of the clips each comprise straight portions which extend parallel to each other in the area of the distal end of the clip, i.e. at its open side. In addition, the clip arms consist of several substantially non-deformable portions which are connected by deformable portions. All known clips have the common feature that each of the clip arms comprises one substantially straight portion and the connecting portion includes two substantially straight portions. Formed in the fillet as well as in the transition zones between the clip arm and the connecting portion are sections which are curved to a greater or lesser extent. What is more, all these clips are single-web clips, namely clips which can be bent out of a piece of wire and extend substantially in a plane (except for a wire beading).
Single-web clips always have two clip arms. It is a problem with such type of clips that they have unfavorable properties in some cases during applying, i.e. in the course of being compressed by a clip applicator. On the one hand, the provision of the quite small radius of curvature in the transition zone from the clip arm to the connecting portion creates a zone in which the material of the clip (a metal, for instance titanium or titanium alloys) is stretched to a greater extent than in the adjacent zones, having the effect that said zone, in the following referred to as a kinked area, cannot be completely re-deformed into the straight shape when compressing the clip with an applicator. Consequently, the compressed clip will have an area where the two clip arms have a larger distance between them. This results in a suboptimal closure of the clipped, i.e. compressed vessel. A further problem with this kind of clips is that the closure of said clips in the compressed state is weak at the distal end of the clip arms. This means that the distal clip ends hardly apply a force onto the vessel, with said force being supposed to result in the closing of the vessel. During the compression procedure, the two parallel clip arms are deformed inwards around the fillet of the clip. In doing so, only the kinked area or the transition zone of the clip remains in contact with the respective branch of the clip applicator. Only if the distal ends of the clip touch each other (in case no tissue is grasped) or come into contact on both sides of the tissue to be grasped (in case tissue is grasped), the kinked area between the clip arm and the connecting portion is bent up. In this process, the distal ends of the clip arm are deformed towards outside and the relevant point of transmitting the force into the tissue is displaced toward the kinked area. This again releases the distal ends of the clip arms, and they will relax from their elastic deformation (while mostly maintaining their current position). If the kinked area in the clip arm has been re-deformed as far as possible, i.e. the clip is completely pressed, this has the effect that the clip is hardly able to apply a closing or compression force at the distal ends of the clip arms, as the distal ends of the clip arms can be easily deformed outwards in elastic fashion and there are zones in the middle region at which the clip arms contact each other (if no tissue is grasped) or the clip arms have a substantially punctiform contact on both sides of the grasped tissue (in the following, this area is referred to as a middle contact area in both cases). In this way, the distal ends have been fully relieved towards the end of the compression procedure, as the kinked area in the clip arm has been re-deformed with a force which by far exceeds the force which is required for bringing the remaining areas of the clip into the compressed shape of the clip. The compression force, which actually should be distributed over the length of the compressed clip as uniformly as possible, will then be concentrated in the vicinity of the clip fillet and the middle contact area of the clip.
The European Patent application EP 1 712 187 A2 shows an instrument head in which the two jaw part branches are connected via a common base in an elastic/resilient manner. In the area of their distal ends which are provided for holding the surgical clip and compressing it and applying the clip in this way, the two branches have their outer side provided with one sliding surface each. For closing the instrument head and applying the clip, the instrument head is displaced in a proximal end direction with respect to the shaft in which it is arranged (i.e. the instrument head is partially pulled into the shaft or the shaft is slipped over the instrument head), and the distal edge of the shaft glides along the sliding surfaces. Due to the fact that the sliding surfaces are inclined with respect to the axis of the shaft, the distal ends of the branches are urged inwards, whereas the proximal ends of the branches are held by the base. In this way, the branches each perform a rotary movement around that point at which the branches are connected to the base. The opening procedure of the instrument head proceeds without any guidance and is exclusively ensured by the elasticity of the branches which are urged back into their initial position if the instrument head is pushed out of the shaft during the opening procedure.
A comparable instrument head is also shown in the International Patent Application WO 2008/127968, even though the instrument illustrated therein differs greatly from the above-described instrument. The rotary movement of the branches during opening and closing the instrument head is still more apparent from the US Patent application US 2005/0171560 A1. According to this document, the distal areas of two branches are articulated on the base and rotate around the fastening point. Also in this construction, the clip is applied by the distal edge of the shaft gliding along the sliding surfaces which are provided on the outer sides of the branches, and in this way presses the branches in inward direction. The problem with this type of instrument heads is that they always have a closing geometry which is always the same, to be more precise, that first the distal ends of the branches make contact with each other or slide past each other; subsequently, those areas of the branches which are arranged to be further proximal make contact with each other or slide past each other. This means in the case of clip applicators that the clip is always closed starting from the distal end. For other surgical instruments such as endoscopic scissors, this structure of an instrument head is not useful for this reason. A further problem relating to this kind of instrument head is that the process of opening the instrument head is solely achieved by the elasticity of the branches. The opening movement of the instrument head is performed without any guidance. If it should happen that a piece of tissue or some other piece gets between the front edge of the shaft and a branch of the instrument head, the opening procedure of the instrument head could be impeded thereby. In that case, it would be necessary to first remove the instrument from the cavity within the patient, to free it of the piece of tissue, and to insert it into the patient again. This entails delays and disturbances in the surgical procedure.